1. Field
The present disclosure relates generally to a cartridge seal and, in particular, to a cartridge seal for a centrifugal pump. Still more particularly, the present disclosure relates to an apparatus and system for using compressed gas in a cartridge seal in a centrifugal pump.
2. Background
Common uses of centrifugal pumps include water, sewage, petroleum, and petrochemical pumping. The pumping of fluids by a centrifugal pump occurs via rotational energy. A centrifugal pump typically converts rotational energy into the energy of a moving fluid via an impeller.
The rotational energy of a centrifugal pump may come from an engine, an electric motor or some other suitable source of rotational energy. The impeller is typically attached to the source of rotational energy via a shaft. As the shaft is forced to spin, the shaft in turn causes the impeller to rotate about the axis of the shaft. Fluid entering the centrifugal pump comes in contact with the rotating impeller. When the fluid comes in contact with the rotating impeller, the fluid gets caught up in blades of the impeller. The rotational force of the impeller causes the fluid to accelerate with increased energy before exiting through the output of the pump.
A structure within a centrifugal pump is typically used to keep fluids from coming in contact with the motor. This structure is normally located between the impeller and the motor with the shaft going through the structure. This structure is sometimes called a gland. A seal is sometimes present at the location where the shaft goes through the structure. Together, the structure and the seal substantially prevent leakage of the fluid around the shaft. While many types of seals have been used for this purpose, cartridge seals are a type of seal that is typically recommended for this purpose.
A spring is typically used to maintain contact of the cartridge seal with the structure. Compression springs are a type of spring normally used in cartridge seals. Compression springs include coil springs and wave springs. These compression springs become shorter when compressed. Compression springs generate a force that resists the compression.
The force generated by a compressed spring is known as elastic energy. When compressed, the amount of elastic energy produced by a compression spring will reduce over time. This loss of elastic energy is known as elastic fatigue. Over time, elastic fatigue of the spring may result in the spring needing to be replaced. The amount of elastic force needed from the spring to prevent leakage, may result in the spring needing to be replaced sooner than desired.
The amount of space available in a cartridge seal for a spring is limited. This space limitation reduces the size of the spring that can be used. The reduction in the size of the spring may result in elastic fatigue occurring faster than desired.
Therefore, it would be advantageous to have an apparatus and system that takes into account at least some of the issues discussed above, as well as other possible issues.